The present invention relates generally to structural metal joint configurations and methods of joining structural members, and more particularly to novel welded tee joints between structural members at least one of which is cylindrical in shape.
Structural tees, welded joints, and other configurations for joining a pair of structural elements in substantial transverse abutting relationship to each other find widespread use in temporary or permanent framework in a multiplicity of applications related to construction equipment including scaffolding, roadway and bridge building forms, and the like, and to fences and railings, to equipment implements, lifts and stands, to structural supports for mining operations, and to industrial machinery and material handling equipment. In the prior art, a variety of configurations exist for joining a pair of cylindrical structural elements, and particularly a pair of cylindrical tubular elements, including hollow cast or forged tees, die cut or drilled and welded configurations, contour or bias cut and welded joints, and the like. Each of these configurations suffer one or more drawbacks rendering each unsuitable for general application. For example, a cast tee provides certain economies in large scale production, but is in general structurally weak. A cast tee may be especially unsuitable for a joint which is subjected to substantial twisting, tension, bending or shock loads; cast tees are generally limited to fluid flow applications. A forged tee overcomes the inherent structural weakness of the cast tee but is characterized by relatively high cost and may be limited in availability in a desired size and geometry.
In the fabrication of a punched or drilled and welded joint, a tee of structural quality may be provided by punching or drilling a hole of predetermined diameter through the wall of a tubular member comprising a transverse member for the tee, inserting the abutting member and welding the two members to form a tee. The special equipment required to punch or to drill through the wall of the transverse member is expensive and not readily available, especially in the fabrication of joints including abutting members of different diameters. Such a joint cannot be made between members wherein a transverse bearing member has a diameter smaller than that of the abutting strut, and the punched and welded joint cannot be made between two solid abutting members; a punched and welded joint is especially unsuitable when the inside surface of the transverse member must retain its integrity, such as to function as a bearing member to receive a smaller diameter cylinder, because the abutting strut member penetrates the wall of the bearing member.
In the fabrication of a contour bias cut and and welded joint, the end of an abutting strut member is cut to conform to the outside surface of the transverse member, and requires careful welding to provide a quality joint. Consequently, the fabrication of this type of joint is unduly time consuming and often results in a joint which is neither square nor structurally sound.
A bias cut and welded joint is formed by making two 45.degree. cuts on the end of the abutting strut member to form two points, and cutting the transverse member to form a notch to receive the strut. Without specialized equipment, substantial problems are encountered in making the two cuts to produce a square joint, and a tubular transverse bearing member in a fabricated joint may not provide an acceptable inner bearing surface without substantial dressing of the inner surface after welding is complete.
The present invention eliminates or substantially reduces in critical importance the foregoing problems in the prior art by providing a joint structure in the form of a fabricated tee and method of fabrication therefor, the fabricated tee characterized by substantial strength and by economy and ease of fabrication.
It is therefore a principal object of the present invention to provide an improved welded structural tee joint between two abutting structural members at least one of which is cylindrical in shape.
It is a further object of the invention to provide an improved welded structural tee joint between two abutting cylindrical or tubular members of substantially any size and wall thickness.
Another object of the invention is to provide a welded joint in which the structural members abut at an angle other than 90.degree..
Another object of the invention is to provide an improved welded joint between cylindrical members of different diameters.
Another object of the invention is to provide an improved welded joint between abutting members having different cross sections.
Yet another object of the invention is to provide an improved welded joint between abutting members having respective longitudinal axes of symmetry which do not intersect.
Another object of the invention is to provide a welded structural joint wherein a tubular transverse bearing member may receive a smaller diameter cylinder to form a bearing.
Another object of the invention is to provide an improved method of fabricating a welded structural joint.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.